Whats the weather like on Titan? Salt flats provide new clues Alan Boyle, Science Editor NBC News 6 hours ago Image: Titan lakes NASA / JPL-Caltech / SSI This false-color mosaic, made from infrared data collected by NASAs Cassini spacecraft during a Sept. 12 flyby, reveals the differences in the composition of surface materials around hydrocarbon lakes at Titan, Saturns largest moon. Fresh images of the hydrocarbon lakes on Titan reveal what appears to be the extraterrestrial equivalent of salt flats — a discovery that adds yet another layer of mystery to Saturns largest moon. Titan is permanently shrouded in a methane-rich haze, making it the only moon in the solar system to have a dense atmosphere. Instruments on NASAs Cassini orbiter, however, can cut through the haze and see what lies beneath. During previous flybys, Cassinis cameras have mapped chilly lakes of methane and ethane in Titans northern hemisphere. The readings have led scientists to believe that theres a hydrologic cycle at work, with hydrocarbons raining down onto the surface, collecting in the lakes, and evaporating back into the atmosphere. In the past, the spacecrafts visual and infrared mapping spectrometer has been able to capture only distant or oblique views of the lakes and surrounding terrain. But during flybys in July and September, the VIMS instrument got a much better view — thanks to seasonal changes on Titan, rain-free weather and an improved viewing geometry. The new images appear to shed light on a key stage of Titans weather cycle — the stage that puts the liquid hydrocarbons back into the atmosphere. Many of these northern liquid bodies are surrounded by a bright material not seen elsewhere on Titan, Carolyn Porco, head of the Cassini imaging team, wrote in an email introducing the new pictures on Wednesday. Is this an indication that with increased warmth, the seas and lakes are starting to evaporate, leaving behind a deposit of organic material ... or, in other words, the Titan equivalent of a salt flat? Image: Titan lake region NASA / JPL-Caltech / SSI An annotated infrared image shows the region around some of Titans northern lakes, and highlights what appear to be evaporite deposits on the surface surrounding the lakes. The evaporites are indicated as false-color orange spots. In the color-coded imagery, the bright material shows up as orange against the greenish backdrop of Titans bedrock of water ice. Scientists suspect that the material consists of organic chemicals that were once suspended in Titans haze. Those chemicals could have dissolved into pools of methane — and when the liquid evaporated, the organics were left behind. Scientists dont yet know exactly what the material is made of. They are the equivalent of salt flats on Earth, but the compounds on Titan arent actually salts since they are probably nonpolar, like methane and ethane themselves, Jason Barnes, a participating scientist for the VIMS instrument at the University of Idaho, told NBC News in an email. Referring to the material as organic simply means it contains carbon atoms. In this context, the term doesnt imply that the stuff was created as a result of lifes processes. However, Titans environment is thought to allow for the kind of prebiotic chemistry that preceded lifes rise on Earth. Titans obscuring haze makes it tricky to trace that chemistry in detail, but Cassini is helping researchers get to the bottom of the mystery. The view from Cassinis visual and infrared mapping spectrometer gives us a holistic view of an area that wed only seen in bits and pieces before and at a lower resolution, Barnes said in a NASA news release. It turns out that Titans north pole is even more interesting than we thought, with a complex interplay of liquids in lakes and seas and deposits left from the evaporation of past lakes and seas.
Posted on: Thu, 24 Oct 2013 05:02:35 +0000
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